In recent years, path networks have occupied the attention of the industry as networks which accommodate traffics of large-capacity efficiently, and the research and development task of developing a path control signaling protocol for setting or deleting paths has been pushed forward. For example, Multi-Protocol Label Switching (MPLS) was researched and developed initiatively by the Internet Engineering Task Force (IETF), and was standardized as IETF RFC (Request for Comments) 3031 (see non-patent document 1), and then implementation thereof to a router and a Layer ⅔ switch has begun. Also, Generalized Multi-Protocol Label Switching (GMPLS) was researched and developed initiatively by the IETF, and was standardized as IETF RFC 3471 (see non-patent document 2), and then implementation thereof to a router, a Layer ⅔ switch, an Optical Cross Connect (OXC), and a Synchronous Optical Network and Synchronous Digital Hierarchy (SONET/SDH) device has begun.
Further, new path control signaling protocols named Optical User Network Interface (OUNI) and GMPLS-UNI (User Network Interface) were developed, and the research and development of GMPLS proceeded so that setting and deleting paths among path networks with different layers became possible. For example, due to the development of the above-described path control signaling protocols, setting or deletion of a path in a packet-based path network from another packet-based path network composed of routers or Layer ⅔ switches via a wavelength-based path network composed of OXCs became possible.
Nowadays, new restoration technology has been investigated. According to the technology, under a condition such that routers are path-connected via an OXC network, a router resets a path responding to a failure occurred in the OXC network or occurred between the router and an OXC.    Non-Patent Document 1: IETF RFC 3031, [online], [searched on Nov. 7, 2005], internet <URL:    ttp://www.ietf.org/rfc/rfc3031.txt>    Non-Patent Document 2: IETF RFC 3471, [online], [searched on Nov. 7, 2005], internet <URL:    http://www.ietf.org/rfc/rfc3471.txt>